双稳态孤子

对于具有一定形式非线性的薛定谔方程，存在单孤子解的多稳态，也就是说对于相同能量，单孤子具有不同的传输常数．本文以一非线住形式Ｌｉｎｅａｒ　Ｓｍｏｏｔｈ　Ｓｔｅｐ（ＬＳＳ）函数为例，对孤子的双稳态进行理论分析，并对其双稳态的光学转换进行数值模拟．     

新型快挥发带电清洗剂对支柱复合绝缘子的溶胀效应及改进

直流硅橡胶绝缘子积污后对其绝缘性能和使用寿命有重要影响,一般通过带电清洗剂进行清洗,而在带电清洗剂下的溶胀效应带来的不利影响是有待解决的关键问题.对1、2号两种带电清洗剂挥发速率、硅橡胶在不同带电清洗剂清洗前后的溶胀性以及憎水性的变化进行了试验研究,并探讨了相应的机制.结果表明:1、2号带电清洗剂在25℃时的挥发速率分别为1095.78 g/(h·m2)和108.01 g/(h·m2);硅橡胶溶胀度随时间的增加而增大,溶胀10 h后达到饱和,饱和后的硅橡胶溶胀指数分别为55％和130％;1号带电清洗剂会削弱硅橡胶的憎水性,经过10 min浸泡,接触角下降了14％,2号带电清洗剂能增强硅橡胶的憎水性,经相同时间浸泡,接触角上升了6％,因而挥发性优良的带电清洗剂可以降低溶胀对硅橡胶绝缘子的不利影响.     

A Dual Physical Cross-Linking Strategy to Construct Tough Hydrogels with High Strength,Excellent Fatigue Resistance,and Stretching-Induced Strengthening Effect

Hydrogels with excellent stiffness, toughness, anti-fatigue, and self-recovery properties are regarded as promising water-containing materials. In this work, a dual physically cross-linked (DPC) sodium alginate (SA)/poly[acrylamide (AAm)-acrylic acid (AAc)-octadecyl methacrylate (OMA)]-Fe³⁺ hydrogel is reported, which is constructed by hydrophobic association (HA) and ionic coordination (IC). The optimal DPC hydrogel demonstrates excellent mechanical performance: tensile modulus of 0.65 MPa, tensile strength of 3.31 MPa, elongation at break of 1547%, and toughness of 27.8 MJ m^–3. SA/P(AAm-AAc-OMA)-Fe³⁺ DPC hydrogels also exhibit prominent anti-fatigue and self-recovery performance (99.1–109.7% modulus recovery and 90.4–108.9% dissipated energy recovery after resting for 5 min without additional stimuli at ambient temperature) through the reconstruction of reversible physical cross-linking. Some of the SA/P(AAm-AAc-OMA)-Fe³⁺ DPC hydrogels even exhibit a stretching-induced strengthening effect, which is similar to the performance of muscle—“the more training, the more strength.” Hence, the combination of HA and IC will provide an effective approach to design DPC hydrogels with desirable mechanical performances and a longer service life for wider applications of soft materials.     

生物陶瓷人工骨制备的新方法

主要介绍了近年来发展起来的两种新技术 :快速原型制造技术和放电等离子烧结技术。概括了两种技术的原理、特点以及在人工骨制备中的应用 ,提出了用这两种技术制备人工骨的设想。     

太阳能喷射-压缩复合制冷系统的实验及仿真

建立了太阳能喷射-压缩复合制冷系统的实验研究平台,基于EES软件程序进行系统稳态仿真,实验验证了仿真模拟程序的正确性,分析了不同发生温度、中间温度对系统性能的影响。研究表明,在中间温度和冷凝温度不变的情况下,随着发生温度的升高,总功率先降低后升高,系统EER先升高后降低;同时,系统COP呈先逐渐升高而后降低的趋势。在研究范围内,最优发生温度工作区域为78~80℃,此时,系统的总耗功量最小;最优中间温度工作区域为7~10℃,此时,系统制冷量达2 245 W,EER最高为3.39。     

The effect of washing process on the cracking of ZrO2 microspheres by internal gelation

ZrO₂ microspheres are widely used as a simulant of UO₂ in the development of nuclear fuel. However, the cracking of ZrO₂ microspheres prepared by internal gelation is still a challenge during drying and sintering processes. To address this issue, we designed and optimized the washing process for obtaining crack-free ZrO₂ microspheres. Through thermogravimetric, infrared, Raman, BET, and SEM analysis, it is shown that the cracking of the microspheres is mainly related to the pores in microspheres. The washing solvent with low surface tension is used to reduce the effect of capillary force on pore shrinkage. Therefore, the optimal washing process was designed as trichloroethylene (TCE)—0.5 M NH₃.H₂O—Propylene glycol methyl ether (PM) and gel microspheres with a high specific surface area of 315.3 m²/g and pore volume of 0.4125 cm³/g were obtained. The characterizations also further showed that when the microspheres were dried and sintered, the water vapor and the decomposition gas of organic matter were completely released from the pores in the microspheres. Our new washing process could be directly extended for preparing crack-free ceramic microspheres by internal gelation.     

Dual-responsive shape memory hydrogels with self-healing and dual-responsive swelling behaviors

Shape memory hydrogels (SMHs) can fix the hydrogels in a provisional shape and restore the initial shape under external stimulation. Herein, a dual-responsive shape memory hydrogel with dual-responsive swelling and self-healing properties is presented in this work. The SMHs were fabricated by one-step emulsion copolymerization of acrylic acid (AAc), acrylamide (AAm) and stearyl methacrylate (SMA). Sodium alginate (SA) was introduced as an interpenetrating polymer in the network. With ionic cross-linking between -COO⁻ and Fe³⁺ or saline-reinforced hydrophobic association, the hydrogels can be fixed in a provisional shape, which can be restored by immersing the hydrogels in vitamin C solution or pure water, respectively. When the as-prepared hydrogels were immersed in FeCl₃ solutions, additional ionic cross-linking between Fe³⁺ and -COO⁻ could be formed, thus constructing the dual physically cross-linked (DPC) network, which endows the hydrogels with excellent fracture stress (2.6 MPa) and toughness (5.47 MJ/m³). Besides, the reversible physical cross-linkings endowed the hydrogel with outstanding self-healing capability. Furthermore, the pH and saline responsive swelling properties of the SMHs are additional fantastic properties. Therefore, we believe that this simple strategy provides a great opportunity for the preparation of SMHs with multiple intellectual performances.     

MIMO-OFDM系统的低阶信道估计的改进

在慢衰落信道条件下,MMSE估计有较好的估计性能但复杂度较高。为了降低信道估计的运算复杂度,分析并总结了原有的MMSE信道估计算法以及其改进算法,提出一个基于MIMO-OFDM系统的OLR-MMSE信道估计算法。OLR-MMSE估计是结合了MMSE算法的低秩近似以及SVD分解,大大降低了大矩阵的阶数,有效地降低运算复杂度并可以保持良好的估计性能。通过计算机模拟仿真验证了提出的信道估计可以达到系统性能和复杂度之间较好的权衡。     

A preliminary attempt to use radiomic features in the diagnosis of extra-articular long head biceps tendinitis

Magnetic Resonance Materials in Physics, Biology and Medicine - This study aims to present a radiomic application in diagnosing the long head of biceps (LHB) tendinitis. Moreover, we evaluated...     

考虑不确定性的结构性市场力评估方法

市场力评估是电力市场化改革的关键环节。随着大规模新能源接入电力系统,电力市场不确定性激增,现有的确定性市场力评估模型向概率性模型转化。由于确定性模型无法考虑新能源的不确定性特征,市场力误判现象频发,严重威胁电力市场的安全运行。为考虑新能源与负荷不确定性的重要影响,提出了一种结构性市场力指标——考虑不确定性的发电机最小期望发电集(UEMGI)。基于机会约束理论,以发电机出力期望最小为目标,提出了考虑不确定性的市场力评估优化模型。然后,基于潮流方程对不确定性的灵敏度分析,通过引入松弛变量对机会约束的非线性部分进行二阶锥松弛,提出了所提机会约束优化模型的二阶锥快速求解方法。最后,采用PJM 5节点和IEEE 39节点系统进行仿真计算。仿真结果表明,所提方法能有效反映系统整体不确定性水平与市场参与者市场力之间的复杂关系,为新能源背景下电力市场的结构性市场力评估提供有效手段。